Scotland’s health secretary, Humza Yousaf, has accused Boris Johnson of announcing an end to England’s Covid restrictions as a blatant attempt to “distract and deflect” attention from the partygate crisis. Yousaf said the policy appeared to have been cooked up at Downing Street with little scientific or expert support. The prime minister had failed to notify the UK’s devolved governments about the move, a signal it was a hasty political decision. “This wasn’t a thought-out policy backed up by public health expert advice, it was a dead cat thrown on the dispatch box of the House of Commons in order to distract and deflect,” Yousaf told BBC Radio 4’s Today programme. He said the Scottish government, which sets its own policies on Covid restrictions, had asked for clarification about the basis of Johnson’s decision but had not yet had any. It had no plans to follow suit, he added. “Since this decision was made – and it was a unilateral decision, one that wasn’t discussed with any of the other three nations of the UK – we’ve asked for that public health advice and none has been forthcoming. “And I think we should just be frank … This was clearly an attempt to deflect scrutiny away from the prime minister’s behaviour.” Johnson told MPs he expected to end England’s self-isolation rules for those infected with, or exposed to, Covid this month, a full month earlier than the 24 March date currently set out in the regulations. A legal requirement to self-isolate will be replaced by unenforceable advice to do so. Scotland’s first minister, Nicola Sturgeon, is due to publish a comprehensive plan on a phased end to Covid restrictions on 22 February. She announced on Thursday that pupils and teachers in secondary schools in Scotland would no longer need to wear face coverings in classrooms from 28 February. Face masks in schools and physical distancing rules in enclosed spaces have been mandatory in Scotland. Prof Andrew Watterson, a public health expert at Stirling University, said Johnson’s proposals were a “leap in the dark” and were out of step with policy across Europe. It would be unwise for Scotland to follow the prime minister’s lead, he said. “It’s almost a big-bang approach by the UK government, a leap in the dark,” he told BBC Radio Scotland on Thursday. “It’s not measured in terms of gradually relaxing the controls, it’s a big leap. But there’s also confusion because it’s quite clear that what’s being called for, and even the prime minister has said this, is not an end to self-isolation, it’s an end to the regulation about it.” The Scottish Conservatives have argued that Sturgeon’s government needs to lift its restrictions sooner, to help businesses recover and allow life to return to normal. They argued it was contradictory for children to wear face coverings for seven hours a day in school while their parents could sit in a pub or office in close proximity to others without face masks. The conflict between the two parties escalated after the Tories complained that Scotland’s chief medical officer, Prof Sir Gregor Smith, had retweeted a political attack by Yousaf on Johnson, in breach of civil service rules on impartiality. In that tweet, Yousaf made the allegation that the prime minister wanted to “distract and deflect”. Smith apologised on Thursday lunchtime, and withdrew his retweet after acknowledging Yousaf’s was political. Russell Findlay, a Scottish Tory MSP, said Sweden was moving in the same direction as Johnson. “Nobody wants to cling on to being under these restrictions for any longer than is necessary,” he said. “Thanks to the booster [vaccination] we are now in a position to move forward and try to live with the pandemic and manage it in a more measured way.”